U.S. Pat. No. 5,363,990 (Fillmore) describes a pump package for containing and simultaneously dispensing two fluent products, specifically, viscous products. The package of this reference has an outer plastic body that is internally divided into two compartments, one for each of the packaged products. The package has a dispensing end through which each of the packaged products is dispensed, and each of the products is caused to flow to the dispensing end by a piston within the compartment in which such product is contained; thus, two such pistons are required for a package that contains two products. Obviously, of course, two piston rods are required to advance the pistons within their respective compartments, one for each piston, and a one-way spring connection is required by each piston and the piston rod that is used to advance it. Moreover, to actuate the movement of the piston rods, a lever system is provided, and the lever system, of necessity, is external to the outer plastic body, since the interior of the plastic body is filled with the packaged products. Thus, the lever system is subject to accidental actuation during shipment of a pump package according to this reference or during its display on a retail shelf.
U.S. Pat. No. 4,801,046 (Miczka) also discloses a package for containing and simultaneously dispensing two fluent products, and teaches that each such product be contained within a collapsible container, both collapsible containers being positioned within an outer container body. The collapsible containers are caused to collapse by the motion of a common piston within the container body. However, the motion of the piston requires that it be pressurized by a gas propellant filling, and such internally pressurized packages are expensive because of the need to be strong enough to be able to contain the propellant, and sufficiently well sealed to be able to do so without leakage.